As defined by the Robot Institute of America, a robot may be a "reprogrammable, multifunctional manipulator designed to move materials, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks." To date virtually all robots have been constructed with rigid frames and the majority are servo-driven, either electrically or hydraulically.
The field of robotics is relatively undeveloped as a technology. Thus, problems continue to arise as attempts are made to apply state of the art robotic technology to increasingly demanding and sophisticated industrial applications. For example, certain applications require the robot to have variable load capabilities. Earlier designs and constructions for robots have not met this specific requirement or have done so unsatisfactorily and thus fail to meet the needs of the industry.
This particular problem with variable load capabilities might best be understood by way of example. When a rigidly framed robot is in a static position and performing a task, the load on the frame is subject to change if a transfer of material, e.g. a fluid, occurs from the robot to a separate apparatus or vice-versa. The transfer of the load causes a dynamic change in the robot's frame despite the static position of the robot itself. If the transfer of load is sufficiently significant, deflection occurs in the rigid frame, and thus the location of the joints of the frame in space will change. Proper performance of the task, however, is generally dependent upon the position of the robot in space. Without adequate feedback as to the dynamic changes occurring throughout the frame, the deflections cannot be compensated for and the position of the robot shifts, thereby jeopardizing the satisfactory performance of the task by the position-dependent robot. The use of the robot thus becomes questionable when it cannot be relied upon to complete the task as intended.
Performance of tasks which create dynamic changes in the frame of an otherwise static robot is an increasing requirement in many industries desiring to use robots. What is necessary then to insure an accurate and reliable performance on the part of the robot is a design and frame construction which can compensate for varying loads during the performance of a task. The present invention is intended to meet such requirements and is believed to advance the state of the art beyond the presently well-known rigid-frame models to a flexible-frame robot construction.